Coerced photodimerization reaction in the solid state through amine salt formation

Article abstract of DOI:10.1016/S0040-4020(03)01140-2

Photodimerization of fumaric or several γ-form trans-cinnamic acids proceeded successfully in the solid state through amine salt formation with ammonia or some aromatic heterocyclic amines (especially, imidazole). It appears that this success is due to a small size or a planar structure of the amine. A layered or a channel-type clathrate crystal structure was revealed, respectively.

Full text of DOI:10.1016/S0040-4020(03)01140-2

Tetrahedron 59 (2003) 7323–7329
Coerced photodimerization reaction in the solid state through
amine salt formation
*
Yoshikatsu Ito, Tetsuya Kitada and Masahiro Horiguchi
Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University,
Katsura, Kyoto 6158510, Japan
Received 31 May 2003; revised 17 July 2003; accepted 23 July 2003
Abstract—Photodimerization of fumaric or several g-form trans-cinnamic acids proceeded successfully in the solid state through amine salt
formation with ammonia or some aromatic heterocyclic amines (especially, imidazole). It appears that this success is due to a small size or a
planar structure of the amine. A layered or a channel-type clathrate crystal structure was revealed, respectively.
q 2003 Elsevier Ltd. All rights reserved.
1. Introduction
2. Results and discussion
Anintriguing feature onthe chemistry oforganic crystalisthat
some of the crystals are reactive and others are unreactive,
even though the difference of their molecular structure is
minor.1 The reactivity and selectivity in the solid state is
mostly controlled by the crystal structure, but unfortunately it
isstilldifficulttoconstructadesiredone.Therefore, anattempt
for developing simple experimental methods to compel
photoinert crystals to be reactive will be of significance. In
this connection, we and others have been investigating
photochemical reactions of two-component crystals.2,3
Fumaric acid (1) is photostable in the solid state, as we
confirmed.† In order to change the reactivity of 1, we
prepared many crystalline salts from 1 and alkylamines
(a–m) having a series of alkyl groups (1/amine¼1:2 or 1:1;
Table 1). These crystals were pulverized and were irradiated
at 254 nm for 40 h under an argon atmosphere. Our method
for the solid-state photolysis was described previously.2,4–6
After the photolysis, product compositions were estimated
by NMR (in DMSO-d6). The results are summarized in
Table 1. It can readily be seen that diammonium fumarate
(1h), i.e. the salt with the smallest amine, underwent
photodimerization to give almost selectively cis,trans,cis-
1,2,3,4-cyclobutanetetracarboxylic acid (CBTA). Other
salts afforded essentially no CBTA. On the other hand,
trans,cis-photoisomerization leading to maleic acid was
achieved relatively easily except 1h and 1i. This is
interesting because trans,cis-photoisomerization of an
alkene double bond is generally inefficient in the solid
state.1
We have already explored orientational control over the
solid-state photodimerization of specific compounds like
trans-cinnamic acids,4 anthracenecarboxylic acids,5 and
trans-cinnamamides6 by using diamines (for the acid case)
or dicarboxylic acids (for the amide case). Diamines and
dicarboxylic acids were expected to function as a non-
covalent linker, i.e. to connect two monomer molecules in a
sort of pre-designed orientation. A problem met there,
however, was that many of those hydrogen-bonded co-
crystals have little or no reactivity. We felt that the main
cause for such a lack of reactivity would be due to the steric
bulkiness of the linker. Hence, we have investigated the
effect of the amine size on the attempted photodimerization
in aminium salts of specific alkenoic acids.7
Keywords: solid state; photodimerization; fumaric acid; cinnamic acid;
amine salt; imidazole.
*
We have found that two kinds of the co-crystal of 1 with
guanidine hydrochloride (H2N)2CvNH·HCl (n) (1/n¼8:1
and 3.7:1 based on the C, H, N, Cl-elemental analysis, mp
229–237 and 208–2268C, respectively) can afford CBTA in
a reasonable yield (CBTA 31 and 25%, 1 66 and 69%,
maleic acid 3 and 6%, respectively). This result suggests
Corresponding author. Tel./fax: þ81-75-383-2718;
e-mail: yito@sbchem.kyoto-u.ac.jp
On the other hand, we found that maleic acid, which was recrystallized
†
from wet benzene, photoreacted in the solid state to give quantitatively
CBTA: 82% conversion after 100 h irradiation of maleic acid (80 mg)
with a low pressure mercury lamp (254 nm) under Ar atmosphere at room
temperature.
0040–4020/$ - see front matter q 2003 Elsevier Ltd. All rights reserved.
doi:10.1016/S0040-4020(03)01140-2

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Y. Ito et al. / Tetrahedron 59 (2003) 7323–7329
Table 1. Product compositions of the solid state photolysis of ammonium fumarates 1a–1m, prepared from fumaric acid (1) and alkylamines a–m
Salt
Amine a–m
1/aminea
Product composition (%)
Fumaric acid (1)
Recovered amine (%)
CBTA
Maleic acid
1a
1b
1c
1d
1e
1f
1g
1h
1i
t-BuNH2
(^)-s-BuNH2
(S)-s-BuNH2
PrNH2
i-PrNH2
EtNH2
MeNH2
1:2
1:2
1:2
1:2
1:2
1:2
1:2
1:2
1:2
1:1
1:1
1:1
1:1
Trace
1
Trace
0
0
0
0
84
0
0
50
35
35
57
63
89
87
15
98
70
63
84
89
50
65
65
43
37
11
13
1
100
100b
100b
97
100
96
96
NH3
nec
100
100
100
100
92
PhCH2NH2
(^)-t-chxn
(S,S)-t-chxn
c-chxn
2
1j
1k
1l
30
37
15
11
0
1
0
1m
Et3N
Irradiation was carried out for 40 h with a 10 W low-pressure mercury lamp at room temperature.
a
Molar ratios based on elemental analysis.
The photolysate melted during irradiation. Irradiation at 08C afforded similar results.
Not estimated.
b
c
that besides the smallest amine (ammonia), planar amines
may be used in order to dimerize 1. We therefore prepared
many aminium salts from 1 employing aromatic hetero-
cyclic amines A–I (1/amine¼1:1 except 1I where it is 1:2;
Table 2). They were irradiated in the solid state and the
results are summarized in Table 2.
heterocyclic amines, except 1G and 1I, produce CBTA with
negligible formation of maleic acid. The salt with imidazole
(A) 1A gave the best result, producing selectively CBTA in
a high yield. In the case of 1C, betaine 2 was formed as a
byproduct, which was decarboxylated into 3 in hot DMSO
(see Scheme 1). It is known that fumaric acid (1) and some
pyridine compounds can react slowly to give betaines, e.g.
pyridine (C) gave 2 in about 20% yield on heating at 508C
for 50 h in methanol.8 The reactivities for the pyridine
compounds were shown to depend on both their basicity and
steric effects.8 The present experiment suggests that 2 can be
formed also by the solid state photolysis, since the crystal
1C is unreactive in the dark. Comparing the pKa values for
A, C, D, E, F, G, H, and I (6.95, 5.25, 0.65, 3.45, 5.53, 4.90,
5.42, and 5.58, respectively), the basicity of C (pKa 5.25) is
medium and thus it cannot rationalize the characteristic
betaine formation observed uniquely in 1C.
Table 2. Product compositions of the solid state photolysis of aminium
fumarates 1A–1I, prepared from fumaric acid (1) and aromatic hetero-
cyclic amines A–I
Salt 1/aminea
Product composition
(%)
Recovered amine
(%)
CBTA Fumaric acid Maleic acid
(1)
1A 1:1
1B 1:1
1C 1:1b
1D 1:1b
1E 1:1
1F 1:1
1G 1:1
1H 1:1
89
27
14
26
13
46
1
11
73
82
72
87
54
99
90
0
Trace
100
100
36d
0d
100
100
100
100
100
0c
2
0
0
Several substituted trans-cinnamic acids, for instance, o-
methyl- (4), m-methoxy- (6), p-methoxy- (7) and m-
chlorocinnamic acid (8),9 are known to take a photoinert
g-crystal modification.‡ The crystal form of m-methylcin-
namic acid (5) is not reported. We irradiated the crystal of 5
(recrystallized from ether) and found only slow and
complex reactions (see the bottom row in Table 3).
Hence, the crystal structure of 5 must be unsuitable for
photodimerization. Now we prepared ammonium salts
4h–8h from these cinnamic acids. The ammonium salt 9h
of unsubstituted trans-cinnamic acid (9) was also prepared
for comparison. The most stable crystal modification of 9 is
known to be an a-structure and is photochemically
converted into a-truxillic acid.9
0
Trace
10
1I
1:2
No reaction
Irradiation was carried out for 40 h with a 10 W low-pressure mercury lamp
at room temperature.
a
Molar ratios based on elemental analysis, unless otherwise specified.
Based on NMR analysis. The elemental analysis gave a value less than
b
unity for the amine component.
Another product: 2, 4%.
Lost during the irradiation.
c
d
To our surprise, all these salts underwent photodimerization
to yield exclusively or mainly head-to-head dimers, i.e. b-
and d-truxinic acids (Table 3). We had previously observed
that many of the double salts of trans-cinnamic acids with
diamines were inert to photodimerization.4 As a result,
ammonia appears to be a very good base to cause
‡
According to the previous paper, 8 is polymorphic: b or g.9 In our hands,
however, we always obtained a g-form. While 7 is photostable in the
crystalline state,9 its photodimerization at the air/solution interface10 or in
vesicles11 proceeded effectively.
Table 2 demonstrates that all of the salts with the aromatic

Y. Ito et al. / Tetrahedron 59 (2003) 7323–7329
7325
Scheme 1.
photodimerization of fumaric and particular trans-cinnamic
acids in the solid state.§
rationalize the efficient photodimerization observed in 1A
(Table 2).
3. Conclusion
In summary, in the successful photodimerization of fumaric
acid or several g-form trans-cinnamic acids in the solid
state, ammonia (i.e. the smallest amine) and some aromatic
heterocyclic amines (especially, imidazole) allowed high
yields of the corresponding dimers to be formed through
amine salt formation. It appears that a small or a planar
complexing agent is a good foreign molecule for converting
photostable crystal packing into photodimerizable.
4. Experimental
4.1. General
1H NMR spectra were measured on a JEOL EX-270J
spectrometer. The solvent employed is DMSO-d6, unless
otherwise specified. IR spectra were recorded with a
SHIMADZU FTIR-8100A spectrometer (in KBr and/or
nujol). Mass spectra were obtained in a JEOL JMS-HX
110A spectrometer. Melting points were measured on a
YANACO MP-S3 microscopic hot-stage and are
uncorrected.
We have already reported the crystal structures of
diammonium fumarate (1h) and bis(isopropylammonium)
fumarate (1e).12 For the photodimerizable 1h, the layer of
ammonium ions (NH4þ) and the layer of fumarate ions
(2O2CCHvCHCO22) aþre alternately arrayed (Fig. 1(A)).
Since the size of NH4 is small, the fumarate ions are
juxtaposed with good overlap. The intermolecular distance
˚
between the CvC double bonds of the fumarate is 3.73 A,
and thus is suitable for the photodimerization.1,13 The
crystal structure of 1e is also layered (Fig. 1(B)). Here,
however, the fumarate layers are far separated from each
other, because the C–N bond in the cation (i-PrNH3þ) is
directed nearly perpendicular to the layers. Thus, the
separation of the pertinent CvC double bonds is longer
4.2. Materials
All the starting compounds weemployed, i.e. fumaric acid (1),
tert-butylamine (a), sec-butylamine (b), (S)-(þ)-sec-butyla-
mine (c), propylamine (d), isopropylamine (e), ethylamine (f),
methylamine (g) (40% MeOH solution), ammonia (h) (28%
aqueous solution), benzylamine (i), trans-1,2-diaminocyclo-
hexane (t-chxn, j), (1S,2S)-(þ)-trans-1,2-diaminocyclohex-
ane ((S,S)-t-chxn, k), cis-1,2-diaminocyclohexane (c-chxn, l),
˚
than 7.2 A, which corresponds with the lack of photodimer-
ization in 1e.{1,13
The X-ray crystal structure of 1A is shown in Figure 2.
There are one molecule of hydrogen fumarate anion
(HO2CCHvCHCO22 ) and one molecule of imidazolium
cation (imidazoleHþ) in the asymmetric unit. Planar
imidazolium cations are stacking along the a axis, forming
a column. Between the columns of the cation, there is a
channel, where the planar hydrogen fumarate anions are
aligned as guest in pairs with good overlap. The inter-
molecular distance between the CvC double bonds of the
Table 3. Product compositions of the solid state photolysis of ammonium
trans-cinnamates 4h–9h
Salt
R
Product composition (%)
h–h dimmer (b,d) h–t dimmer (1)a
Cis
18
4
0
Trans
4h
5h
6h
7h
8h
9h
5
o-Me
m-Me
47 (13, 34)
62 (29, 33)
m-Ome 100 (22, 78)
0 (0)
1 (1)
0 (0)
0 (0)
0 (0)
7 (7)
0 (0)
34
33
0
˚
p-Ome
m-Cl
H
68 (68, 0)
79 (79, 0)
90 (80, 10)
4 (4, 0)
0
0
14b
0b
fumarate pair is 3.76 A. These structural data can well
3
Trace
0
75b
§
However, we could not obtain a crystalline ammonium salt from caffeic
{ or ferulic acid.
m-Me
The crystal structure of 1m was also reported.14 It was assignedþas
Irradiation was carried out for 10 h with a 400 W high-pressure mercury
lamp at 108C.
triethylammonium hydrogen fumarate (HO2CCHvCHCO22 )(Et3NH ).
a
˚
Fumarate double bonds are nonparallel and more than 4.5 A away, which
explains1,13 the absence of CBTA from 1m (Table 1).
The a isomer was undetectable in all cases.
Polymeric materials were also formed.
b

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Y. Ito et al. / Tetrahedron 59 (2003) 7323–7329
Figure 1. The crystal structures of (A) diammonium fumarate (1h) and (B) bis(isopropylammonium) fumarate (1e). The figures are somewhat modified from
those reported in Ref. 12.
triethylamine (m), guanidine hydrochloride (n), imidazole
(A), 1,2,4-triazole (B), pyridine (C), pyrazine (D), 2-
aminopyrimidine (E), benzimidazole (F), quinoline (G),
isoquinoline (H), acridine (I), o-methylcinnamic acid (4),
m-methylcinnamic acid (5), m-methoxycinnamic acid (6),
p-methoxycinnamic acid (7), m-chlorocinnamic acid (8),
and trans-cinnamic acid (9), were purchased from the
commercial sources.
4.3. Preparation of salt crystals
A warm solution containing 742 mg (6.39 mmol) of 1 in
MeOH (10 mL) was mixed with a solution containing
871 mg (12.79 mmol) of imidazole (A) in MeOH (10 mL)
and the hot mixture was filtered immediately. Upon
cooling to room temperature, colorless prisms crystal-
lized out of the filtrate and were collected by filtration to
afford 793 mg (67%) of the salt 1A. This was dried in
vacuo at room temperature for 20 h and characterized by
1H NMR (DMSO-d6), IR (KBr), and elemental analyses.
This crystal showed a complex melting behavior, starting
to melt above 1928C, then resolidified around 2108C, and
finally decomposed at 278–2818C. The NMR spectrum
was a superposition of the spectra of 1 and A. A strong IR
frequency corresponding to the CO22 group was observed
at 1585 cm21. The molar ratio of the constituents was
determined by the NMR and elemental analyses to be
1:1.
All the other salts were similarly prepared and character-
ized. Detailed data for the solvents which were used for
mixing and recrystallization, mp, the molar ratio of the
constituents, IR (1500–1650 cm21 region), and the elemen-
tal analysis are summarized in Tables 4–9. From inspection
of the IR data, 1m as well as most of the salts of 1 with
aromatic heterocyclic amines except 1A showed no strong,
broad absorption corresponding to the CO22 group at 1500–
1650 cm21 region. Therefore, these salts may be more
appropriately called hydrogen-bonded cocrystals. However,
Figure 2. The crystal structure of imidazolium hydrogen fumarate (1A).
Broken lines indicate hydrogen bonds.

Y. Ito et al. / Tetrahedron 59 (2003) 7323–7329
7327
Table 4. Preparation of fumaric acid/amine salt crystals 1a–1n, prepared from fumaric acid (1) and alkylamines a–m and guanidine hydrochloride (n)
Salt
Amine
Solvent
Mp (8C)
1/aminea
IR frequencyb (cm21)
Mixing
i-PrOH
EtOH
EtOH
EtOH
EtOH
Recrystznc
1a
1b
1c
1d
1e
1f
1g
1h
1i
1j
1k
1l
1m
1n(1)
1n(2)
t-BuNH2
EtOHþMeOH
EtOHþEt2O
EtOHþEt2O
EtOH
.223 (sublim)
166.5–168.5
168–171
163.5–167
201–205
185.5–187.5
188–200
243–254
1:2
1:2
1:2
1:2
1:2
1555
s-BuNH2
(S)-s-BuNH2
PrNH2
i-PrNH2
EtNH2
MeNH2
NH3
PhCH2NH2
t-chxn
(S,S)-t-chxn
c-chxn
Et3N
1632, 1560, 1525
1632, 1560, 1525
1584, 1509
1560
1560, 1535
1559, 1538d
1577
1566, 1526
1587
1561
1586, 1560
1632d
EtOH
EtOHþH2O
EtOHþMeOHþH2O
i-PrOHþH2O
EtOH
EtOHþH2O
EtOHþMeOHþH2O
MeOHþH2Oe
MeOH
1:2þ0.1(H2O)
1:2
1:2
1:2
1:1
178–184
MeOH
EtOH
MeOHþH2O
MeOHþH2O
MeOHþH2O
i-PrOHþEt2O
MeOH, first crop
Second crop
.213 (unclear)
212–221
195–203
75–99
229–237 (dec)
208–226 (dec)
1:1.05þ0.16(H2O)
1:1þ0.45(H2O)
1:1
EtOH
i-PrOHþEt2O
(H2N)2CvNH·HCl
MeOHþH2O
8:1þ0.5(H2O)
Not measured
Not measured
3.7:1þ0.4(H2O)
a
Molar ratios based on the elemental analysis (Table 7).
1500–1650 cm21 region corresponding to the CO22 and/or –NHþ3 groups: in KBr, unless otherwise specified.
The resultant crystals were dried in vacuo at room temperature, unless otherwise specified.
In nujol.
Air-dried at room temperature.
b
c
d
e
1m is a hydrogen fumarate, judging from the X-ray
4.3.1. Photoproducts. Irradiations were made under argon
atmosphere in a vessel described previously,2 with a 10 W
low-pressure mercury lamp through quartz or with a 400 W
high-pressure mercury lamp through Pyrex. Photolysates
were analyzed by 1H NMR (in DMSO-d6) and characterized
in general by direct comparison with authentic samples. The
crystallographic structural analysis.{ So far, the crystal
structures for 1e (Fig. 1(B)),12 1h (Fig. 1(A)),12 1m,14 and
1A (Fig. 2) were determined. Further studies by the single
crystal X-ray analysis are in progress, including those for
several ammonium cinnamates.
Table 5. Preparation of aminium fumarates 1A–1I from fumaric acid (1) and aromatic heterocyclic amines A–I
Salt
Amine
Solvent
Mp (8C)
1/aminea
IR frequencyb (cm21
1635, 1585
)
Mixing
MeOH
Recrystznc
MeOH
1A
Unclear (.192)
1:1
1B
1C
MeOH
MeOH
MeOH
183–208
1:1.06
1:1e
1640, 1515
MeOHd
.242 (sublim)
No evident peaksf
1D
1E
1F
MeOH
MeOH
MeOH
MeOHd
MeOH
MeOH
.230 (sublim)
.244 (sublim)
182–184
1:0.86
1:1
No evident peaksf
1628, 1560
1:1
1625, 1525
1G
1H
1I
MeOH
MeOH
MeOH
MeOH
MeOH
MeOH
.230 (sublim)
.215 (sublim)
194–202
1:1
1:1
1:2
1644, 1595, 1508
1646
1623, 1568, 1522
a
Molar ratios based on the elemental analysis (Table 8), unless otherwise specified.
1500–1650 cm21 region.
The resultant crystals were dried in vacuo at room temperature.
A part of the heterocyclic amine was lost on drying and the samples turned opaque.
From NMR.
In nujol.
b
c
d
e
f

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Y. Ito et al. / Tetrahedron 59 (2003) 7323–7329
Table 6. Preparation of ammonium trans-cinnamates 4h–9h from trans-cinnamic acids 4–9 and ammonia (h)
Mpa (8C)
Acid/NH3
IR frequencyc (cm21)
b
Salt
R
Solvent
Mixing
Recrystznd
4h
5h
6h
7h
8h
9h
o-Me
m-Me
m-OMe
p-OMe
m-Cl
MeOHþH2O
MeOHþH2O
MeOHþH2O
MeOHþH2O
MeOHþH2O
MeOHþH2O
i-PrOHþEt2OþH2O
MeOHþH2O
i-PrOH
MeOHþH2O
MeOHþH2O
i-PrOH
173–175
116–120
88–90
175–178
160–161
133–135
1:0.93
1:0.97
1:1
1:1
1:1
1525
1530
1520
1535
1520
1530
H
1:0.82
a
The melting point for 4h, 5h, 7h, 8h, and 9h is virtually the same as that of the corresponding parent acid. In fact, ammonia was slowly lost on exposure of
4 h–9h to air.
b
c
d
Molar ratios based on the elemental analysis (Table 9).
The absorption corresponding to the CO22 group: in nujol.
The resultant crystals of 6h–9h were dried in vacuo at room temperature for a short period of time (1–2 h), while those of 4h and 5h were only air-dried since
NH3 was especially easily lost.
authentic sample of cis,trans,cis-1,2,3,4-cyclobutanetetra-
(6 H, s, Me); IR (film) 1733 (CO2Me), 1436, 1211, 1165,
755 cm21; MS (FABþ, NBA) m/z (rel intensity) 353 (100,
(MþH)þ), 176 (62), 145 (46, [MeO2CCHvCHCO2Meþ
H]þ); HRMS (FABþ, NBA) calcd for C22H25O4 353.1753,
found 353.1752 ((MþH)þ). 2,20-Dimethyl-d-truxinic acid
exhibited 1H NMR (DMSO-d6, 270 MHz) peaks at d 7.46–
7.00 (8 H, m, aromatic), 3.44 (2 H, quasi-d, J¼9.5 Hz,
cyclobutyl), 2.99 (2 H, quasi-d, J¼9.5 Hz, cyclobutyl), and
2.00 (6 H, s, Me). This compound was methylated with
methanol during the chromatographic separation with silica
gel, giving 10.
carboxylic acid (CBTA) was obtained from the solid state
photodimerization of dimethyl fumarate followed by
hydrolysis with conc HCl.15 Betaines 2 and 3 were prepared
according to the literature method.8 The stereochemistry of
the truxinic or truxillic dimers of trans-cinnamic acids 4–8
1
was assigned on the basis of the characteristic H NMR
chemical shift and coupling pattern of the cyclobutyl
protons.4,6a,16 They were very similar to those of the
dimers of unsubstituted trans-cinnamic acid (9), which were
available from our previous work.4 Dimethyl 2,20-dimethyl-
d-truxinate (10), 3,30-dimethyl-d-truxinic acid (11), 3,30-
dimethyl-b-truxinic acid (12), and 3,30-dimethoxy-d-truxinic
acid (13) were separated by preparative TLC on silica gel
(MeOH–CHCl3) or by preparative HPLC (Asahipak GS-
0
1
3,3 -Dimethyl-d-truxinic acid (11): H NMR (DMSO-d6,
270 MHz) d 7.18–6.95 (8 H, m, aromatic), 3.32 (2 H, quasi-
d, J¼9.2 Hz, cyclobutyl), 2.78 (2 H, quasi-d, J¼9.2 Hz,
cyclobutyl), 2.25 (6 H, s, Me); IR (KBr) 1700 (CO2H),
1606, 1564, 1411, 1252, 1021, 782, 700 cm21; MS (FABþ,
DTT/TG) m/z (rel intensity) 325 (21, (MþH)þ), 209 (100,
[MeC6H4CHvCHC6H4MeþH]þ); HRMS (FAB2, TEA)
calcd for C20H19O4 323.1283, found 323.1288 ((M2H)2).
1
320, MeOH) and their H NMR, IR, and MS spectra are
given below. 2,20-Dimethyl-d-truxinic acid was spon-
taneously esterified with methanol into the dimethyl ester
10 during the separation procedure.
Dimethyl 2,20-dimethyl-d-truxinate (10): 1H NMR (DMSO-
d6, 270 MHz) d 7.54 (2 H, d, J¼8.5 Hz), 7.24 (2 H, t,
J¼8.5 Hz), 7.11 (2 H, t, J¼8.5 Hz), 7.06 (2 H, d, J¼8.5 Hz),
3.82 (2 H, quasi-d, J¼9.7 Hz, cyclobutyl), 3.61 (6 H, s,
CO2Me), 3.48 (2 H, quasi-d, J¼9.7 Hz, cyclobutyl), 1.96
0
1
3,3 -Dimethyl-b-truxinic acid (12): H NMR (DMSO-d6,
270 MHz) d 6.93 (2 H, t, J¼7.7 Hz), 6.83 (2 H, s), 6.79 (4 H,
d, J¼7.7 Hz), 3.98 (2 H, quasi-d, J¼6.6 Hz, cyclobutyl),
3.55 (2 H, quasi-d, J¼6.6 Hz, cyclobutyl), 2.12 (6 H, s, Me);
IR (KBr) 1716 (CO2H), 1606, 1409, 1226, 779, 699 cm21
;
MS (FABþ, TEA) m/z (rel intensity) 325 (56, (MþH)þ),
209 (100, [MeC6H4CHvCHC6H4MeþH]þ); HRMS
(FABþ, TEA) calcd for C20H21O4 325.1440, found
325.1439 ((MþH)þ).
Table 7. Analytical data for fumaric acid/amine salt crystals 1a–1n,
prepared from fumaric acid (1) and alkylamines a–m and guanidine
hydrochloride (n)
Calcd (%)a
H
Found (%)
H
C
N
C
N
3,30-Dimethoxy-d-truxinic acid (13): white solid, mp 224–
1
1a
1b
1c
1d
1e
1f
1g
1h
1i
54.94
54.94
54.94
51.26
51.26
46.19
40.44
32.00
65.44
52.16
51.79
50.39
55.28
9.99 10.68
9.99 10.68
9.99 10.68
9.46 11.96
9.46 11.96
8.82 13.46
7.92 15.72
6.71 18.66
54.77
54.82
54.82
51.17
51.08
46.19
40.34
31.81
65.27
51.92
51.86
50.41
55.00
9.83 10.41
9.79 10.60
9.79 10.48
9.24 11.90
9.33 11.74
8.88 13.46
7.73 15.60
6.53 18.46
226 8C (from CHCl3): H NMR (DMSO-d6, 270 MHz) d
Table 8. Analytical data for aminium fumarates 1A–1I, prepared from
fumaric acid (1) and aromatic heterocyclic amines A–I
Calcd (%)a
H
Found (%)
H
C
N
C
N
6.71
8.48
6.78
8.43
1j
1k
1l
7.88 12.17
8.03 12.31
7.99 11.75
8.02 12.10
8.31 12.24
7.86 11.48
1A
1B
1D
1E
1F
1G
1H
1I
45.66
38.84
48.32
45.50
56.41
63.67
63.67
75.94
4.38
3.82
4.05
4.30
4.30
4.52
4.52
4.67
15.21
23.53
13.03
19.90
11.96
5.71
45.52
38.66
48.32
45.71
56.30
63.78
63.69
76.22
4.45
3.87
4.08
4.17
4.40
4.41
4.43
4.79
15.50
23.55
13.00
20.18
11.92
5.78
1m
8.81
6.45
8.82
6.22
4.14
7.76
1n(1) 38.37 Cl, 3.43 3.80
1n(2) 35.66 Cl, 6.66 4.09
4.07b 38.41 Cl, 3.39 3.86
7.90c 35.67 Cl, 6.85 4.12
5.71
5.90
5.63
5.89
a
See Table 4 for the 1/amine ratio.
(1)8((H2N)2CvNH·HCl)1(H2O)0.5
b
.
(1)3.7((H2N)2CvNH·HCl)1(H2O)0.4
c
a
.
See Table 5 for 1/amine ratio.

Y. Ito et al. / Tetrahedron 59 (2003) 7323–7329
7329
3. Tanaka, K.; Toda, F. Chem. Rev. 2000, 100, 1025–1074.
Table 9. Analytical data for ammonium trans-cinnamates 4h–9h, prepared
from trans-cinnamic acids 4–9 and ammonia (h)
4. (a) Ito, Y.; Borecka, B.; Scheffer, J. R.; Trotter, J. Tetrahedron
Lett. 1995, 36, 6083–6086. (b) Ito, Y.; Borecka, B.; Olovsson,
G.; Trotter, J.; Scheffer, J. R. Tetrahedron Lett. 1995, 36,
6087–6090.
Salt
Calcd (%)a
Found (%)
C
H
N
C
H
N
4h
5h
6h
7h
8h
9h
67.47
67.21
61.53
61.53
7.24 7.32 67.20
7.28 7.60 67.17
6.71 7.18 61.42
6.71 7.18 61.45
7.20 7.17
7.09 7.54
6.62 6.99
6.58 7.13
5. (a) Ito, Y.; Olovsson, G. J. Chem. Soc., Perkin Trans. 1 1997,
127–133. (b) Ito, Y. Mol. Cryst. Liq. Cryst. 1996, 277,
247–253.
6. (a) Ito, Y.; Hosomi, H.; Ohba, S. Tetrahedron 2000, 56,
6833–6844. (b) Ohba, S.; Hosomi, H.; Ito, Y. J. Am. Chem.
Soc. 2001, 123, 6349–6352.
54.15 Cl, 17.76 5.05 7.02 54.39 Cl, 17.81 5.02 6.97
66.68 6.50 7.08 66.73 6.52 7.11
a
See Table 6 for the acid/NH3 ratio.
7. For recent examples on supramolecular control of photo-
dimerization, see the following papers. For stilbene deriva-
tives: (a) Amirsakis, D. G.; Garcia-Garibay, M. A.; Rowan,
S. J.; Stoddart, J. F.; White, A. J. P.; Williams, D. J. Angew.
Chem., Int. Ed. Engl. 2001, 40, 4256–4261. (b) Amirsakis,
D. G.; Elizarov, A. M.; Garcia-Garibay, M. A.; Glink, P. T.;
Stoddart, J. F.; White, A. J. P.; Williams, D. J. Angew. Chem.,
Int. Ed. Engl. 2003, 42, 1126–1132. (c) Bassani, D. M.;
Sallenave, X.; Darcos, V.; Desvergne, J.-P. J. Chem. Soc.,
Chem. Commun. 2001, 1446–1447. (d) Jon, S. Y.; Ko, Y. H.;
Park, S. H.; Kim, H.-J.; Kim, K. J. Chem. Soc., Chem.
Commun. 2001, 1938–1939. For cinnamic acid derivatives:
(e) Bassani, D. M.; Darcos, V.; Mahony, S.; Desvergne, J.-P.
J. Am. Chem. Soc. 2000, 122, 8795–8796. (f) Zitt, H.; Dix, I.;
Hopf, H.; Jones, P. G. Eur. J. Org. Chem. 2002, 2298–2307.
For bis(pyridyl)ethylene derivatives: (g) MacGillivray, L. R.;
Reid, J. L.; Ripmeester, J. A. J. Am. Chem. Soc. 2000, 122,
7817–7818. (h) Varshney, D. B.; Papaefstathiou, G. S.;
MacGillivray, L. R. J. Chem. Soc., Chem. Commun. 2002,
1964–1965. (i) Friscic, T.; MacGillivray, L. R. J. Chem. Soc.,
Chem. Commun. 2003, 1306–1307. (j) Ohtani, O.; Katoh, H.;
Takagi, K. Chem. Lett. 2002, 48–49. (k) Shan, N.; Jones, W.
Tetrahedron Lett. 2003, 44, 3687–3689. For coumarins: (l)
Tanaka, K.; Mochizuki, E.; Yasui, N.; Kai, Y.; Miyahara, I.;
Hirotsu, K.; Toda, F. Tetrahedron 2000, 56, 6853–6865. For
anthracenes: (m) Wu, D.-Y.; Chen, B.; Fu, X.-G.; Wu, L.-Z.;
Zhang, L.-P.; Tung, C.-H. Org. Lett. 2003, 5, 1075–1077. (n)
Tung, C.-H.; Wu, L.-Z.; Zhang, L.-P.; Chen, B. Acc. Chem.
Res. 2003, 36, 39–47.
7.16 (2 H, t, J¼8.0 Hz), 6.90 (2 H, s), 6.87 (2 H, d,
J¼8.0 Hz), 6.73 (2 H, d, J¼8.0 Hz), 3.72 (6 H, s, OMe),
3.32 (2 H, quasi-d, J¼9.5 Hz, cyclobutyl), 2.77 (2 H, quasi-
d, J¼9.5 Hz, cyclobutyl); IR (KBr) 1720 (CO2H), 1607,
1580, 1290, 1054, 779, 696 cm21; MS (FABþ, DTT/TG)
m/z (rel intensity) 357 (100, (MþH)þ), 241 (88,
[MeOC6H4CHvCHC6H4OMeþH]þ); HRMS (FAB2,
TEA) calcd for C20H19O6 355.1182, found 355.1190
((M2H)2).
4.4. Determination of the X-ray crystal structure of 1A
X-Ray intensities were measured on MacScience
DIP2030K diffractometer (IP radius 150 mm) with graphite
˚
monochromatized MoKa radiation (l¼0.71073 A). The
structure was solved and refined using maXus. Crystal data:
ꢀ
C7H8O4N2, M¼184.151, triclinic, P1 a¼7.4860(5),
˚
b¼7.7590(3), c¼8.4290(6) A, a¼69.710(4)8, b¼81.403(4)8,
3
3
˚
g¼66.168(4)8, V¼420.03(5) A , Z¼2, Dx¼1.456 g/cm ,
m¼0.121 mm21, 1826 measured reflections, R¼0.042,
Rw¼0.098 for 1707 reflections [I . 3sðIÞ with 151
parameters]. Crystallographic data for 1A have been
deposited with the Cambridge Crystallographic Data
Center, deposition number 206967. Copies of the data can
be obtained, free of charge, on application to CCDC, 12
Union Road, Cambridge CB2 1EZ, UK [fax: þ44(0)-1223-
336033 or e-mail: deposit@ccdc.cam.ac.uk].
8. Streba, E.; Luca, C.; Holerca˜, M. N.; Ba˜rboiu, V.; Simionescu,
C. I. Rev. Roum. Chim. 1997, 42, 413–420.
Acknowledgements
9. Cohen, M. D.; Schmidt, G. M. J.; Sonntag, F. I. J. Chem. Soc.
1964, 2000–2013.
This work was supported by the Grant-in-Aid for Scientific
Research (B) from the Japanese Government (No.
10440215). The authors thank Bruker AXS Co. for the
single crystal X-ray diffraction of 1A. Technical assistance
by Mr Yasuhiro Shindo, Hironari Nakabayashi, and Masato
Inumae is also acknowledged.
10. Weissbuch, I.; Leiserowitz, L.; Lahav, M. J. Am. Chem. Soc.
1991, 113, 8941–8943.
11. Nakamura, T.; Takagi, K.; Itoh, M.; Fujita, K.; Katsu, H.;
Imae, T.; Sawaki, Y. J. Chem. Soc., Perkin Trans. 2 1997,
2751–2755.
12. Hosomi, H.; Ito, Y.; Ohba, S. Acta Crystallogr. 1998, C54,
142–145.
13. Schmidt, G. M. J. Pure Appl. Chem. 1971, 27, 647–678.
14. Hosomi, H.; Ohba, S.; Ito, Y. Acta Crystallogr. 2000, C56,
e139.
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